Small Engines (Lawn Mowers, etc.): Rough Idle Briggs and Stratton lawn mower, briggs and stratton, repairfaq

Question
My self propelled mower with a B & S engine model# 12H882 starts up ok but then revs and slows constantly. It doesn't settle down to just a steady idle.

Answer
This is a very common dirty carburetor symptom.  Have you removed, dis-assembled and cleaned the carb with compressed air and carburetor cleaner?

The procedure for cleaning carbs is the same.  If you google "Tecumseh carburetor rebuild" you will find some good links.

Check out this link:
http://www.repairfaq.org/sam/lmfaq.htm

Let me know if the link helps.
Eric